Gas mileage: 87 octane vs non-alcohol grades

[garyash]

I've noticed that when I spend the extra $0.10 to $0.20 per gallon for higher grade gas, that my gas mileage goes up a lot. Massachusetts doesn't have cheap gas, so regular 87 octane might be $3.53/gallon vs $3.73/gallon for 89 octane. So, thats 5.6% more per gallon for the higher grade gas.

My 2008 Taurus with 3.5 liter V-6 gets about 20.8 mpg with the 87 octane from Mobil, about 23-24 mpg with the 89 octane from Sunoco. That's about 13% mileage improvement. I commute about 56 miles each way to work, so I put a lot of miles on the car and it has a reasonably accurate digital mileage gauge. I know it's not just the brand of gas. Does moving up in grade/octane rating really get rid of the alcohol content and yield the better mileage? Are EPA and other agencies screwing drivers with the ethanol content in the name of "clean energy" when we really burn more gas and make more pollution with ethanol in the gas? I have to conclude that it's worth spending a little more on better gas because it makes sense economically. I'll bet a whole nickel that the car manufacturers' mileage ratings are for non-alcohol gas.

Let the flames begin, LOL!

[Flashback]

KINDA HATE TO COMMENT, But, You are spot on. Not only your Tarus, but all my vehicles, have the same response. I know we will get pounded, but it's FACT.

[sweetolbob]

KINDA HATE TO COMMENT, But, You are spot on. Not only your Tarus, but all my vehicles, have the same response. I know we will get pounded, but it's FACT.

I don't know about the pounding but even if the 87 had alcohol and the 89 didn't, there would not be a 13% difference in energy level in the gasolines. I'm more inclined to believe that Gary's car is sensing the ability to run with better advance curves and the engine is preforming at 13% higher efficiency.

I will add that when it comes to mandating mileage levels and automotive efficiency that it has become terribly obvious that science was not consulted prior to the implementation. It's terribly obvious in the newer Class 8 trucks when you look at the amount of mileage and maintenance issues created by the new regulations on EGR.

Bob

[Jim B PEI]

I kept close records of one car in the fleet that is just old enough not to have the latest computer engine management wizardry. Its a regularly and well serviced 2004 Subaru Forester 2.5L 4 cyl 5 sp manual all wheel drive with 200,000 km (125,000 miles), and switching from 87 which may or may not have up to 10% ethanol in it to midgrade 89 which might have 0 to 5% ethanol in it, was a steady price difference of about 3% per grade. Last week reg 87 was $1.21.7, mid 89 $1.25.4 and premium 91 $1.28.9, (and diesel $1.26.5 a litre.) Multiply that by 3.785 for a US gallon, and you can thank your lucky stars you have cheap Massachusetts fuel! (Actually, PEI isn't all that outrageous for Canada--always cheaper than Newfoundland, Nova Scotia, New Brunswick and Quebec)

The 3% price difference of 89 over 87 resulted in a steady 9-10% increase in mileage, maybe 11% when it was mid grade without ethanol for about 4% more than 87. Opting for premium 91 at a total of 6% more than regular 87 only netted about 11-12% better mileage overall-- For this case, midgrade was the best bang for the buck, and midgrade without ethanol was still worth the slight extra additional amount, because the car just runs better with more power. I measured this over a full year 25,000 km (15K miles) and these were very dependable results--the car is used the same way almost all of the time. This is a car DESIGNED to run on US-87 octane, so I'm putting the difference irrespective of the stated octane on the pumps, as being due to the ethanol

I haven't kept as close records in the Studebakers, but there is a dependable power and mileage improvement running ethanol free mid grade or premium, for both the 6s and the V8. When I was taking notes, there was a similar sort of improvement. I usually run a mix of mid and premium in the Studebakers, with some additions like MMO etc. Air-cooled lawntractor 4 cycle and snowblower 2 cycle get premium all the time--not taking a chance with them

Since I drive a VW TDI diesel 5 speed wagon for everyday that usually averages 50 US mpg, I can afford to run premium in the Studebakers <g>

This is an interesting chart: http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent
It explains why I drive a diesel, because it helps explain why diesels just get much better mileage than something gasoline and ethanol powered.

[stephenj]

I started using Ethanol free Shell gas this summer and both Studebakers start with the first turn of the key or push of the button. They both run smoothly with no stalling.

[jnormanh]

Modern cars with their sophisticated fuel injection and ignition systems will run on pretty much whatever grade and octane you feed them. Give them higher octane, and they'll adjust fuel delivery and spark advance to take advantage of the higher octane for more power and better mileage.

My wife's Volvo V70 208HP and 3400# and will do 28-29 mpg on the highway, almost identical to the '69 VW Beetle (53hp AND 1700#) we once owned. The Volvo squeezes every bit of energy out of the fuel it burns, the VW not nearly as efficient.

[jclary]

$3.53 per gallon! sheesh!...my last three fill-ups were at $2.76 per gallon. I still think it is at least $2.00 per gallon too high!

(After reading this, don't you Yankee's get any ideas 'bout moving down here...opps! too late...seems most of you already have.)

[StudeDave57]

$3.53 per gallon! sheesh!...my last three fill-ups were at $2.76 per gallon.

Then you would NOT wanna fill up where I live--- my last three fillups were all OVER $3.75 a gallon!!! And that was at an AM/PM~ it's higher for other brands. I have yet to figure it out- there are FIVE refineries within 40 miles of here.
Go figure!!!!

[Drummerboy]

Like Stephenj in the above post, I was using Shell ethanol free gas until I realized that it came out of the same pump as the ethanol stuff. I believe that the first bit of gas flow still contains a bit of the ethanol flavored stuff. Since then I have been going to Chevron which has a dedicated pump for the ethanol free gas. As far as gas mileage goes, I have noticed only a slight improvement.

[Nelsen Motorsports]

While the alcohol in gas is, in fact, bad. There is one advantage to E-85. E-85 is cheaper in a race engine if built right. A high compression engine (13:1) will run just as good or better on the cheapo E-85 than on 110 octane.

In regular cars my experience has been that the gas mileage gains are good enough with non-ethanol gas to buy it. There are 2 stations with the good stuff less than 5 miles from my house and my Stude definantly has better performance with real gasoline than with E-10.

By the way, never spill ethanol gas on you, it burns and leaves marks on your skin for a day or so.

[tbirdtbird]

My nephew and I consistently get better mileage and performance on real gasoline, which is the real way to decrease emissions: don't burn as much fuel! Duh! Oklahoma and Texas have a few stations which are ethanol free. Most of you are probably aware of this web site, and you can click to zoom and get more detail:

http://www.historicvehicle.org/Commissions/Commissions/Legislative/Pure-Gas-Map

[Lothar]

In Nebraska, "straight" unleaded is 87 octane ($3.59 Gal.) and E-10 unleaded is 89 octane ($3.49). I don't think that I've ever seen more than a 5% mileage difference between these fuels with any of the vehicles I've regularly driven (mostly older American-made pickups and sedans). On the other hand, assuming even a 5% difference in mileage, at the current fuel price level of around $3.50/Gal., you need the price differential to be .18 per gallon to break even in terms of dollars and cents per mile, which is a critical consideration, IMHO.
I guess that, based purely on economics, I should quit buying ethanol gas. I buy ethanol because I'd rather enrich American farmers than prople in other countries whose governments oppose the USA (Canada and Mexico excepted). I don't use ethanol in my Studebaker, my Johnson outboard or my lawn mower, but I use it in my modern vehicles with no problem.
I also realize that I'm fortunate to live in a state (and a "Corn Belt" state, no less!) where you can choose between E-10 and regular unleaded at any gas station.